If your Tecweigh WP20 says MEMORY bad, defaults, the calibration is gone from the unit: factory settings have loaded, and every tonne it shows is meaningless until it’s set up and calibrated again. If it says RAM bad, FLASH ok, it has rebuilt the settings from its last saved backup, which may be older than your last calibration. Self test pass means nothing has changed.
We’re an independent service company, not a Tecweigh dealer or agent. For bookings and parts, see Tecweigh belt weigher and WP-series servicing. For the other messages, see Tecweigh WP20 and WP25 fault codes and calibration and what the messages on a Tecweigh WP50 mean.
What do the WP20 power-up messages mean?
The WP20 keeps your settings in two places: working memory (RAM), which loses its contents without power, and a backup (flash), which doesn’t. At power up it tests both and reports which survived. The Australian and US editions of the manual word the results differently, so both are shown.
| Message | What we check first | When to call us |
|---|---|---|
| Self test pass (US: SELF TEST – PASS) | Nothing. Memory is fine and nothing has changed. | No need. |
| RAM bad, FLASH ok (US: RAM BAD, FLASH RESTORE) | The settings were reloaded from the backup. When was it last saved? Drop the calibration weight and compare the rate with the last recorded figure. | If the rate doesn’t match, or nobody knows when the backup was saved. |
| MEMORY bad, defaults (US: RAM/FLASH BAD, DEFAULTS) | Both copies were lost and factory settings loaded. Note the time and find your recorded settings. | Straight away. The scale needs setting up and calibrating. |
| NO UNITS (US edition only) | Both copies were lost and the restore failed, so all zeros loaded. Defaults must be restored by hand. | Straight away. |
RAM bad, FLASH ok: is the calibration still good?
The recovery worked as designed. Whether the numbers are right depends on how old the backup is. Saving it is a separate manual step, and the manual says to repeat it after every parameter change and every re-zero. The confirmation reads parameters saved on one page of the Australian manual and params saved on another. The same menu shows defaults restored when factory settings are loaded and memory restored when the saved copy is recalled.
If the save was missed after the last visit, the scale is now running older settings than the ones on your last calibration report, and nothing on site will tell you. The rate looks sensible, the totals climb, and the only sign was a message at a power up nobody saw.
An ordinary power cut doesn’t wipe the settings, so a missed save can go unnoticed for months, waiting for the day the memory is genuinely disturbed. We see it after storm seasons often enough that it isn’t a freak event.
MEMORY bad, defaults: are today’s tonnes any good?
No. The unit looks healthy: the display is lit, the rate moves and the total climbs. But a processor on factory settings doesn’t know your belt length, weigh span or calibration weight. The manual notes that a weigh span or belt length left at zero gives a wrong calibration and a wrong rate with no message, which is exactly where a defaulted unit sits.
So the hours since that message are unmeasured, not low. Write down when it appeared, because that’s the window someone will have to account for.
Why does my WP25 or WP50 only ever say self test pass?
Those manuals only publish the passing result, so we won’t guess at what a failure looks like. That’s a gap in the documents, not proof the check can’t fail.
On a WP25, self test passed shows briefly after power up. A SELF TEST message at other times points to an electrical problem: shorted terminals, auxiliary equipment drawing too much current, or wiring run too close to high voltage or motor cables.
On a WP50, SELF CHECK – PASS shows at power up (the manual also calls it SELF TEST and self test passed). It also appears after any reboot, so if it shows mid shift with nobody at the panel, the processor restarted itself. That’s worth chasing.
What makes a Tecweigh lose its settings?
The manual puts it down to a battery failure or an electrical spike, and a nearby lightning strike counts. The tell-tale after a spike is a parameter where one digit won’t change. It looks like a dead keypad but isn’t. Reducing the exposure is about everything upstream of the processor: see protecting belt weigher electronics.
Two causes are self inflicted. Cutting the power during a WP50 fieldbus protocol change can corrupt the flash memory. And after a firmware update from a very old version, the WP50 manual recommends resetting to factory defaults, re-entering the parameters and recalibrating, after recording every parameter first.
How do you tell whether the scale is running your last calibration?
All of this is looking, not changing. Start with the maker’s own check: compare the running rate with the calibration weight down against the figure recorded at the last calibration. A routine span that has moved more than about 0.25% needs attention. It only works if someone wrote the number down. See how to read your calibration report.
- WP20: the zero counts and span counts are viewable, read-only parameters. Compare them with the last visit’s figures. A mismatch is a strong hint, not proof.
- WP25: an internal calibration log records every accepted calibration with the date, time and reference figures. When it fills, the oldest records are deleted, and the same menu has an erase option.
- WP50: accepted zeros and spans are logged to flash, and the security menu shows the date and time of the last parameter save. Dates are only as good as the unit’s clock.
For what zero, span and repeatability mean, see belt weigher calibration tolerance.
What should we do before anyone presses reset or loads defaults?
Work on or near a conveyor, or inside an electrical enclosure, needs isolation under your site’s procedures and trained, authorised people. If that’s not you, stop and call us on 1300 101 666.
Record first: both manuals say to have the current settings available before defaulting a processor. What the manuals then offer, as process rather than keystrokes (keys and menus move between editions):
- Australian WP20: for scrambled values, a reset on the board, which recovers from flash where it can, then a full power disconnect and reconnect.
- WP25: the same board reset, then power off with the RAM battery out for a few minutes, and only then is the processor treated as faulty. The recovery menu sits behind the security level: see locked out of your integrator.
- US WP20: a keypad reload of the defaults and, failing that, a hard boot with the battery and power removed for about a minute.
- WP50: power off for several seconds, then watch for the self test on the way back up.
Anything recovered is only as current as the last save and still has to be proved. Anything defaulted is a full setup and calibration.
How do you stop a memory fault turning into a recommission?
Keep a copy of the settings outside the processor. The Australian WP20 manual has a blank record sheet at the back for exactly this. A WP50 can also save its settings to a USB drive, with the save dated. A WP20’s internal save is a single undated copy, so its age can only come from a paper record.
We record the settings and as-found and as-left figures for every scale we look after in AIMM, our asset management system. With a record, a defaulted processor is a reload and a proving run with the calibration weight. Without one, it’s set up and calibrated from scratch, whoever does it.
We supply parts for Tecweigh and the other major belt weigher brands: a genuine part where it’s available, or a suitable alternative, with compatibility confirmed and the part identified on the quote.
Need a manual for your equipment?
The WP20 manual exists in Australian and US editions that word these messages differently and carry different recovery steps, so note which one you hold. The blank parameter record sheet at the back is the page worth copying.
Talk to us about manuals for your equipment. Send the make, model, serial number and software version (a photo of the label is fine) and we’ll help you find the right document.
When should you call us?
Call when a processor has loaded defaults, when it has restored from a backup and the rate with the weight down no longer matches the record, when a digit won’t change, or when nobody has a record of the settings. Don’t press anything that writes until the current settings are written down. If a board has failed, we’ll tell you straight whether to repair it or replace it. Call 1300 101 666 or email admin@accurateindustries.com.au with a photo of the screen. See booking a belt weigher service.
Frequently asked questions
Does a Tecweigh lose its calibration when the power goes off?
No. An ordinary power cut doesn’t wipe the settings. They’re lost when the memory is disturbed, by a battery failure or a spike, and then the processor reloads whatever was last saved.
My WP20 came up on default settings. Can you get the old calibration back?
Only from a record. If the settings were written down, or we hold them, it’s a reload and a proving run. If not, the scale has to be set up and calibrated again.
What does params saved mean on a WP20?
The current settings have been written to the backup. Do it after every calibration, re-zero and parameter change.
Do I have to recalibrate after a memory fault?
After defaults, yes: full setup and calibration. After a restore from backup, prove it with the calibration weight against the last recorded figure. Treat the tonnes since the message as unchecked until then.